Any intervention into the human vasculature that uses a guidewire or medical device attached to a guidewire may require back-loading the catheter during the course of the medical procedure. Back loading a guidewire into a catheter from the distal end of the catheter to an exit port positioned proximal from the distal end of the catheter can be difficult without a guiding means. To facilitate back-loading, a guidewire lumen, separate from the catheter main body, may be used. Such a separate lumen can run from proximate the distal end of the catheter to a desired exit location proximate the guidewire entry location.
Medical apparatus, such as distal protection devices, are utilized in both over-the-wire and rapid exchange type catheters. While, typically, there are no unique problems encountered during deployment of such devices, problems can be encountered during device retrieval after an interventional procedure.
During the course of a medical procedure, the need may arise to capture debris, such as grumous matter, emboli, thrombi from the affected vessel. Filters of various types have found use, for example, in trapping blood clots and other debris released into the blood stream. Filters are traps that have been designed to be used to collect dislodged matter such as described above. They serve to provide protection from distal embolization that might result in a major adverse coronary event or other acute complication. Embolization of debris which might be released during such procedures and the resulting sequellae have been described in reports documenting major adverse cardiac event rates. Such events include acute myocardial infarction, revascularization and even death.
In order to address such acute embolic-related complications, distal filtration and protection devices have been developed. Such devices have been designed to work with existing interventional modalities. Such devices provide debris-filtering protection during invasive procedures and are intended to prevent complications of particulate embolization.
Such distal filtration and protection devices are typically deployed at a location along a vessel of the body at a desired location. Such deployment is performed by extending the device outwardly from the distal end of a catheter. In order to facilitate deployment, the device to be deployed typically has components made from a shape-memory or highly elastic material. Consequently, they are able to be collapsed within the catheter and, upon being urged outwardly beyond the distal end of the catheter, they reassume their uncollapsed shape.
Once in place, the protection device performs the function of filtering debris as discussed above. Retrieval of a debris-filled filter offers unique problems.
Since the retrieval of a distal protection device requires a minimum inside diameter to remove the device filled with captured debris, it can be difficult to retrieve a device into a recovery catheter. In order to facilitate back-loading, a separate guidewire lumen may be used. Such a lumen must be configured, however, to be retracted within the catheter main body to afford access to the distal protection device during retrieval. If the lumen does not move, or allow retrieval of the distal protection device into the catheter main body, the captured debris will not be properly retrieved into the distal end of the recovery catheter.
Alternatively, debris may be removed from the distal protection device by means of suction while the distal protection device is still deployed in the vasculature. Suction through the catheter main body could aspirate captured debris from the distal protection device using a syringe or similar device attached to the proximal end of the catheter. Since the main body could be sealed off from the guidewire lumen, pressure losses would not occur resulting in decreased aspiration performance.
No device has yet been developed which is effective to accomplish debris removal in a simple manner.